I printed the same art last week (inked) and today (inkless). I haven’t changed any settings on the press. Today’s impression has lost the crispness of the other. Is this an effect of humidity? My press is in an unairconditioned garage and I live in the south. Would a dehumidifier help or do I need a small air conditioner? Or am I totally off on what the problem is? Thanks in advance for help!

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I would also like some expert knowledge on how best to print in humid conditions - could anyone shed any light on how paper, ink and presses may be affected by humidity?

To answer this, it would help to know the total history of the paper: when you bought it, was it all bought at the same time, where was it stored before the first printing, where was it stored before the second printing, and where were the printed sheets from the first printing stored (mainly regarding the temperature and estimated humidity levels of the storage spaces). Did you keep track of which side of the paper was up and print the same side both times? From the shadows of the texture of the paper, it looks like the shadows run about 30 degrees from the horizontal on the left hand sample and about 60 degrees from the horizontal on the right hand sample…..can you account for this in anything you did in cutting the paper, etc.?

Generally, paper becomes softer as humidity increases, and becomes easier to print. This is why we sometimes moisten paper before printing.

It looks like the uninked impression may be deeper than the inked impression. Is it? This might be accounted for if the paper were moister and softer for the uninked “print.” With softer paper, the image may have been able to push farther into the paper, even though no press settings were changed. If this happened, maybe the shoulder angle of the edges of the images on the plate, caused the impressed image to spread and look “flared out,” (if you know what I mean).

Thanks for the reply, Geoffrey! The paper on each sample in the photo is the same—110lb Lettra, purchased from Neenah maybe a month ago. I now keep the paper in a closet in my house, which is air-conditioned, usually around 78 degrees. At one point, the paper was in the garage, but I think I brought it inside even before printing the first one (inked). The garage has not feel humid until today. Rain is in the forecast and temps are rising here. I didn’t keep track of which side of the paper, but tried both sides today and the result was similar. Both sheets were 8.5x11 from the ream, so I can’t think of anything different cutting-wise.

The uninked impression does looked deeper than the first. When I saw the soft, flared impression, I took some packing out from behind the tympan, but the next tries still had a similar result. Wondering if we should get the wrenches out and adjust the settings? (It’s a c&p 10x15).

Could you try taking out more packing from behind the tympan? That would be preferable to adjusting the platen. Then maybe we could rule out the possibility that a deeper impression on the second print was the cause.

You don’t think that excessive wear had occurred to the plate by the end of the first run, do you? If so, that might have played a role in the problem.

Regarding paper conditions, the rule of thumb is to bring the paper into the pressroom and let it acclimate for at least 24 hours before printing on it. I guess that would be the garage in your case. Paper will pick up and give off moisture depending on the environment it is in. In a perfect world I think it would be preferable to have a consistent temperature and humidity, but on the other hand, printers have been practicing their trade for hundreds of years without climate controlled conditions. If you wanted to spend the $$$ to get a dehumidifier and a humidity indicator (available at hardware stores), that certainly wouldn’t hurt.

However, we still haven’t determined whether the environment’s influence on the paper caused the problem.

Wish I could just say that (such and such) is the cause of the problem, but unfortunately I can’t. Maybe someone else will have some ideas as well.

Having lived in the south I sympathize with your problem. A thick, pulpy paper like you show will react dramatically to changes of weather, especially a rise in humidity which can cause it to ‘puff-up’ and expand, making registration very difficult.

I once was printing from dampened paper at my home in middle Tennessee and watching a storm roll in; the extra moisture in the air caused the paper I was using (handmade washi) to expand a full quarter inch. One of the devilish things about printing is the frustration of running a job one day with no problems, and the next day, without any observable changes the job prints completely different.

Keeping your paper in the house, then moving to the shop just before printing is asking for trouble, but dealing with humidity is a problem that can only be fixed in a controlled atmosphere. Air conditioning, and a dehumidifier should help this somewhat, but if your garage is unfinished and uninsulated, with a concrete floor poured on the ground it will be difficult to control. Watch for weather changes, and be prepared to do new make-ready whenever it is necessary, it’s all part of the occupational hazards.


Modern AC was developed for the printing industry:

“In 1902, the first modern electrical air conditioning unit was invented by Willis Carrier in Buffalo, New York. …Carrier began experimenting with air conditioning as a way to solve an application problem for the Sackett-Wilhelms Lithographing and Publishing Company in Brooklyn, New York, and the first “air conditioner”, designed and built in Buffalo by Carrier, began working on 17 July 1902.

Designed to improve manufacturing process control in a printing plant, Carrier’s invention controlled not only temperature but also humidity. … The air blowing over the cold coils cooled the air, and one could thereby control the amount of moisture the colder air could hold. In turn, the humidity in the room could be controlled. The low heat and humidity helped maintain consistent paper dimensions and ink alignment. “

“The environmental conditions of your paper storage and pressroom can have an impact on what is often the largest, most expensive component of a printing project—paper. By nature paper is dimensionally unstable and susceptible to temperature and humidity. As the climate in the air changes, so does the climate within the paper. Establishing policy and procedures to ensure paper is in an optimum condition prior to handling in the pressroom will help to avoid potential problems in production.”

Thanks, all, for the responses! My husband and I will address all the feedback this weekend and try to improve my ‘pressroom.’ I’m definitely learning every day in this craft. Very interesting to know that AC was invented for printing! Thanks again!

One more question: Dehumidifier vs. Air Conditioning. As the dehumidifier is less expensive, we’d love to start with that. Will we get the same effect or should we just bite the bullet and get an AC unit?

I’d certainly get the AC.

Dehumidifiers generate heat, but unlike AC units they don’t usually have the condenser section outside the building to keep the heat from increasing inside.

There are portable all in-one units that are both air conditioners and dehumidifiers. I have one for my garage studio. Works great and cools and dehumidifies the space really well.

If you have more than one garage bay it might be worth considering walling off one bay to make a studio space so you can better control your studio environment.

i use a Dehumidifier that works good but the best way i think is to wrap the paper again in its owne packing unless your second run is right away mostly if i use carbonless paper or self-adhesive paper that tends to absorbe.i work in all conditions without any problems.but of course it is more comfortable to work in a controlled environment with AC